Ellipsograph.



No. 75,883. Patented Dec. I6, I902.

a. w. SHERMAN. ELLIPSOGBAPH.

(Application filed Sept. 29. 1899.)

(No Model.)

WITNESSES.-

' w. Wi ATTORNEY.

'ruz Noams Farms cu, vnoTo-uwo. wAsmncTom o, c.

UNITED STATEs PATENT OFFICE.

GEORGE W. SHERMAN, OF FALL RIVER, MASSACHUSETTS.

ELLIPISOGRAPH.

SPECIFICATION formingpart of Letters Patent No. 715,883, dated December16, 1902. Application filed September 29, 1899. Serial No. 732,040. (Nomodel.)

To all whom it may concern:

Be it known that I, GEORGE W. SHERMAN, a citizen of the United States,residing at Fall River, inthe county of Bristol and State ofMassachusetts, have invented certain new and useful Improvements inEllipsographs, of which the following is a specification.

My invention is intended to provide a simple and efficient device forgenerating ellipses of any desired size and eccentricity and may bedescribed in a general way as consisting of means for describing acircle about an adj ustable axis, combined with means for projectingsaid circle on the plane of the surface to be drawn on, which projectionin accordance with a Well-known geometrical proposition will be anellipse whenever its plane lies at an angle to that of the circleprojected, the size and eccentricity of the ellipse being dependent uponthe radius of said circle and the angle between its plane and that ofthe surface to be drawn on.

An ellipsograph embodying a preferred form of my invention isillustrated in the accompanying drawings, in which Figure 1 is a sideelevation of the complete device. Fig. 2 is a top plan View thereof, andFig. 3 is a detail in section on the line :2 in Fig. 1.

For describing the circle which is to be projected into the desiredellipse I provide an arm 2, journaled on an axis or pivot 3, which issupported by a fixed base 4 and is angularly adjustable with respectthereto. In order to confine the motion of the arm 2 with accuracy tothe desired plane, I prefer to enlarge the pivoted end of said arm intoa fiat disk 5, adapted to bear against a corresponding flat head 6,carried by the base 4, into which head the axis 3, on which the arm 2turns, may be screwed, as shown in Fig. 3.

Thus the motion of the arm 2 will be accu-' rately limited to the planedetermined by the fiat top face of the head 6, which head is madeadjustable, preferably by being provided with a downwardly-projectingsemicircular web 7, having a dovetailed tenon 8 formed thereon andfitted to slide ina corresponding dovetailed groove 9 formed in theupper end of the supporting-base 4. In order to clamp the head 6 in anydesired position of adjustment,

the upper end of the base 4 may be split, as shown at 10 in Fig. 3, andprovided with a clamping-screw 11, passed through the split portionthereof. I prefer to have the base 4 rest on three legs 12, lying in thesame straight line, each leg being provided with an adjustableneedle-point 13, adapted to enter slightly into the paper or othersurface 14, on which the ellipse is to be drawn, thereby holding thisportion of the instrument fixed while the rest of the device is beingrotated, as hereinafter described. As thus constructed the adjust-- ablehead 6 may be so set and clamped as to provide for the accurate motionof the arm 2 in a complete circle and in a plane making L head 6, andwill be projected onthe surface 14 by said middle needle-point. Ifdesired, a graduated scale 15 may be formed on or attached to the top ofthe base a to indicate the angle to which the arm 2 has been adjustedwith respect to the surface 14.

The aforesaid parts being constructed as described, it will be evident.that if any given' point in the arm 2 be projected in all positions ofsaid arm on the surface 14 by any suitable device acting perpendicularlyto said surface the circle described by said given point upon thecomplete rotation of the arm 2 will be projected on the surface 14 as anellipse of which the middle needle-point 13 will be the center. To thisend I provide a rod 16, so arranged that it may be moved bodily aroundthe base 4 as acenter and may approach thereto and recede therefrom, butwill always be kept perpendicular to the surface on which said baserests, and I provide suitable connections between said rod and the arm2, so constructed that said rod 16 will be maintained at a predetermineddistance from the axis 3, but will be capable of the necessary pivotalmovements with respect to the arm 2 when revolved around the base 4.

For this purpose I prefer to form a journal 17 on the upright portion ofthe base 4 and perpendicular to the surface 14, on which journal a frame18 is mounted so that it may be rotated like a pair of compasses bymeans of a thumb-piece 19. Another frame 20 is hinged to the frame 18,as at 21, the pivot of said hinge being parallel to the journal 17, andthe rod 16 is clamped in and carried by said frame 20, as shown, in suchmanner that it will be parallel with the hinge 21 and journal 17 in allpositions of said parts. A considerable space is provided between theends of the frame 20 to permit of the necessary motions of a sleeve 23,hereinafter described, and the frame 18 is similarly formed to provideroom for the parts 5, 6, 7, and 8. A pencil, pen, or other suitablemarking device 22 is carried by the lower end of the rod 16, and saidrod and the needle-points 13 are to be so adjusted that said markingdevice 22 may be kept in proper contact with the surface 14 while theframes 18 and 20 are moved completely around the journal 17 as a centralaxis. During such motion the hinge 21 will obviously keep the rod 16always perpendicular to the surface 14, but will permit of its motiontoward and from the base 4 as a center.

In order to transmit to the arm 2 the rotatory motion to be given to theframes 18 and 20 through the thumb-piece 19, the arm 2 may be connectedto the rod 10; but during such rotatory motion the arm 2 will have avertical motion along the rod 16 and also two angular movements withrespect thereto-one about its own length as an axis and the other aboutan axis perpendicular to its intersection with the rod 1(3-and toprovide for such relative movements and at the same time keep the rod 16at a predetermined distance from the axis 3, measured along the arm 2, Iprefer to mount a sleeve 23 to slide easily but accurately upon the rod16, which sleeve is pivoted to another sleeve 24, mounted to turn easilyon a collar 25 on the arm 2, which collar may he slid along said arm andclamped by a set-screw 26 at any desired point thereon. The sleeve 2&may be kept in place on the collar 25 by confining it between flanges orcollars secured to the ends of the latter, as shown in Figs. 1 and 2,and it will be understood that the sleeves 23 and 24: are pivotedtogether in such manner as not to interfere with the sliding of thesleeve 23 up and down the rod 10 or the rotation of the sleeve 24; onthe collar 25 or the movement of said collar when desired along the arm2. This may conveniently be done by passing a strap 27 around the sleeve23 and securing said strap to the sleeve 24, the pivot 28 being screwedinto the sleeve 23 and arranged to turn in said Strap.

To draw a given ellipse with the device above described, the base 4 isplaced on the surface 14: with the central needle-point 13 coadjustedthatit will make proper contact with the surface 14. The instrumentisthen turned on the journal 17 until the arm 2 is parallel with thesurface 14, and the collar 25, carrying the rod 16 with it, is thenmoved along said arm until the marking device 22 is at one extremity ofthe major axis of the desired ellipse, at which point said collar 25 isclamped firmly to the arm 2. The instrument is next turned on thejournal 17 through an angle of ninety degrees, and the head 6, carryingwith it thearm 2, is then adjusted to such an angle as will cause themarking device 22 to coincide with one extremity of the minor axis ofthe ellipse, and thereupon said head 6 is clamped by the screw 11. Ifnow the frame 18 be rotated by means of the thumb-piece 19 after themanner of a pair of compasses, the frame 20 and rod 16 will be carriedalong therewith and will in turn cause the arm 2 to move through acircle in the plane to which it is adjusted, the head 6 of courseremaining stationary, so that the collar 25, being held at a fixeddistance from the center on which the arm 2 turns, will cause the rod 16and marking device 22 to approach and recede from the base at, accordingto the inclination of the arm 2 to the surface 14, the sleeve 23 at thesame time sliding up and down on the rod 16. The result will be that thecircle described by the point at which the collar 25 is clamped will beprojected on the surface 14 as the ellipse desired and will be describedthereon by the marking device 22, as will be apparent without furtherdescription.

I claim as my invention 1. In an ellipsograph, the combination of a headhaving a downwardly-extending, semicircular web, a fixed base having itsupper end formed on an are described from the same center as that ofsaid web and adapted to guide the latter, means for clamping said weband base together, an arm journaled on said head, at the center of theare on which said Web is formed, a rod pivotally connected with said armand carrying a marking device, and means for maintaining said rodperpendicular to the plane of the desired ellipse and for moving thesame about said fixed base as a center.

2. An ellipsograph comprising in combination a fixed base, an armadjustably pivoted thereon, a collar adjustable on said arm and carryinga rotatable sleeve, a rod provided with a marking device and with asecond sleeve adapted to slide thereon, said two sleeves being pivotedtogether, and means for maintaining said rod perpendicular to the planeof the desired ellipse, and for causing it to revolve about said fixedbase, substantially as described.

3. An ellipsograph comprising in combination a fixed base carryinganadjustable head, base and provided with a thumb-piece, all IO an armpivoted on said head and provided Substantially as described. with anadjustable collar, a sleeve adapted to In testimony whereof I havehereunto subturn on said collar and pivoted to a second scribed my namethis 28th day of September,

5 sleeve, a rod on which said second sleeve is 1899.

adapted to slide and carrying a marking de- GEO. W. SHERMAN. vice at itslower end, and a hinged frame, one Witnesses: portion of which carriessaid rod and the other FRANCIS 'W. OLOUGH,

portion of which is journaled on said fixed E. D. CHADWIOK.

